The lawsuit charged that between January and November of 2005, Sony BMG made more than 12.6 million music CDs embedded with secret DRM software that limited the number of times songs could be copied.
Nothing about the software was mentioned on CD packaging, even though it installed itself in hidden files on users' computers, according to California Attorney General Bill Lockyer.
The program made computers with Windows operating systems vulnerable to hacking and other problems, the lawsuit charged.
Compounding the problem, efforts to remove the software without an uninstall program eventually released by Sony BMG tended to damage computers, according to Lockyer.
Lockyer's office estimated that 450,000 California residents purchased CDs with the DRM software and said that the number of computers damaged was unknown.
"Companies that want to load their CDs with software that limits the ability to copy music should fully inform consumers about it, not hide it, and make sure it doesn't inflict security vulnerabilities on computers," Lockyer said in a release.
"To its credit, Sony BMG learned this lesson and has stopped the practices that led to this lawsuit."